Energy efficiency :: One of the twin pillars of sustainable energy

Efficient energy use, sometimes simply called energy efficiency, is using less energy to provide the same level of energy service. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature. Another example would be installing fluorescent lights and/or skylights instead of incandescent lights to attain the same level of illumination. A 13 watt fluorescent light bulb outputs the same amount of visible light as a 60 watt incandescent bulb, so you are getting the same amount light for less energy. Efficient energy use is achieved primarily by means of a more efficient technology or processes rather than by changes in individual behaviour.

Energy efficient buildings, industrial processes and transportation could reduce the world's energy needs in 2050 by one third, and help controlling global emissions of greenhouse gases, according to the International Energy Agency.